1. Field of the Invention
The invention relates generally to a process for storing solar energy in organic compounds containing carbon and hydrogen, and more particularly to such a process wherein a form of solar energy is used to activate water.
2. Description of the Related Art
Photosynthesis is the process by which plants and certain micro-organisms use solar energy for the conversion of carbon dioxide and water to organic molecules that serve as stores for energy. Examples of such organic compounds include sugars, starch, cellulose, triglycerides, resins, and the like.
Mankind is almost 100% dependent on photosynthesis for its energy needs. The energy required by the human body in the form of food is either a direct product of photosynthesis (all foods of plant origin), or is an indirect photosynthesis product (meat, milk, and other animal food sources). Energy used for heating and for propelling machinery is also almost always derived from photosynthesis, be it in the form of biomass or fossil fuels. The most notable exceptions are solar energy, wind energy and nuclear energy, which do not rely on photosynthesis.
Mankind's dependence on natural photosynthesis for its supplying its energy needs has serious drawbacks. The use of fossil fuels releases carbon dioxide into the atmosphere, which is believed to contribute to climate changes. The use of biomass can be carbon-neutral, but plants are relatively inefficient in converting solar energy to organic molecules. This is due in part to the fact that chlorophyll, the molecule that is responsible for adsorbing solar energy in almost all plants, can absorb only a fraction of the sun's light in the visible part of the spectrum and nothing on other parts of the spectrum, such as infrared or ultraviolet radiation. It is estimated that plants use only about 3% of the solar energy they receive.
Another drawback of natural photosynthesis is that plants require specific conditions in terms of temperature and atmosphere for optimum growth. Thus, photosynthesis is slow at temperatures below about 10° C., and virtually non-existent at temperatures below 0° C. Similarly, at temperatures above about 30° C. plants are challenged to absorb enough water from the soil to allow them to keep up with the evaporation through their leaves. Many plants slow down their photosynthesis during hot weather in order to protect themselves from drying out.
Plants also require an adequate supply of water of a reasonably high quality. With the exception of certain aquatic plants, land based plants generally do not tolerate salt any better than they tolerate droughts. An over-supply of water is also problematic; crops may be lost to flooding just as easily as crops are lost to droughts.
Finally, plants need a balanced supply of minerals and spore elements for their wellbeing. These nutrients need to be supplied by the soil in which the plants grow, and often need to be supplemented by fertilizers.
In summary, the use of plants for mankind's energy needs faces many obstacles and limitations.
Thus, there is a need for a process for storing solar energy in organic molecules. There is a particular need for a process that is more robust than the chlorophyll-based process in terms of temperature requirements. There is a further need for such a process that allows the use of contaminated water.